A process for the preparation of an at least bis-carbamate-functional triazine has been known from U.S. Pat. No. 5,705,641. An “at least bis-carbamate-functional triazine” is a 1,3,5-triazine having at least two functional groups which are carbamate groups. This process involves reacting an amino-functional 1,3,5-triazine having at least two amino groups with an acyclic organic carbonate, in the presence of a base. Useful bases as mentioned in this patent are alkali metal hydrides, alkali metal alkoxides, alkali metal hydroxides, alkali metal oxides, alkali metal carbonates, quaternary ammonium alkoxides, quaternary ammonium hydroxides, quaternary phosphonium alkoxides, quaternary phosphonium hydroxides, tertiary amines, and mixtures thereof. Sodium and potassium alkoxides are most preferred, and include linear, branched and cyclic alkyl group containing alkoxides and mixtures thereof. The reaction may be carried out in a solvent; as useful solvents, alcohol, ether, hydrocarbon, and amide solvents, such as N,N-dialkylformamide, are mentioned; alcohol solvents are preferred and include methanol, ethanol, propanol, butanol, pentanol, and hexanol; and also diols, viz., ethylene glycol, 1,2- and 1,3-propylene glycol, 1,4- and 2,3-butylene glycol, and isomers or mixtures of these. In the examples, n-butanol, methanol, N,N-dimethyl formamide, ethanol, sec.-butyl alcohol, isopropyl alcohol, and 2-ethylhexyl alcohol are used.
It has been found in the experiments on which the present invention is based that excessively high viscosity occurs during the reaction which leads to excessive energy consumption for homogenisation during the reaction, and either the need to use special equipment such as thin film reactors or kneaders, or the need to the use of more diluted reaction mixtures with the consequent loss in space-time yield. It has therefore been desired to reduce the viscosity of the reaction mixture without having to resort to lower concentrations, or having to use special equipment. Reduced viscosity, in other words, enhanced flowability and hence, easier transferability of the reaction mixture allows to increase the concentration of the reactants while maintaining a viscosity which allows simple handling of the reaction mixture, and thus also to increase the concentration of the desired reaction product in the reaction product mixture, thereby increasing the space-time yield for the reaction.
Additionally, this increased flowability allows more efficient neutralisation due to easier and faster mixing in a wider temperature range.